1. Field of the Invention
The present invention relates to coil parts, and more particularly, to coil parts and methods of fabricating the same, which can improve process and productivity and cut fabrication costs by preventing process defects that occur during the fabrication process of a coil part using a ferrite substrate.
2. Description of the Related Art
Electronic products, such as digital TVs, smart phones and notebook computers, have functions for data communication in radio-frequency (RF) bands. Such IT electronic products are expected to be more widely used because they have multifunctional and complex features by connecting not only one device but also USBs and other communication ports.
For higher-speed data communication, data are communicated through more internal signal lines over GHz RF channels higher than MHz channels.
When more data are communicated between a main device and a peripheral device over a GHz RF channel, it is difficult to provide smooth data processing due to a signal delay and other noises.
In order to solve the above problem, an electromagnetic interference (EMI) prevention part is provided around the connection between an IT device and a peripheral device. However, conventional EMI prevention parts are used only in limited fields such as large-area substrates because they are coil-type and stack-type and have large chip part sizes and poor electrical characteristics. What is therefore required is EMI prevention parts that are suitable for the slim, miniaturized, complex and multifunctional features of electronic products.
A common-mode filter of a conventional EMI prevention coil part is described below in detail with reference to FIG. 1.
Referring to FIG. 1, a conventional common-mode filter includes a first magnetic substrate 1, a dielectric layer 2 disposed on the magnetic substrate 1 and including a first coil pattern 2a and a second coil pattern 2b that are vertically symmetrical to each other, and a second magnetic substrate 3 disposed on the dielectric layer 2.
Herein, the dielectric layer 2 including the first coil pattern 2a and the second coil pattern 2b is formed on the first magnetic substrate 1 through a thin-film process. An example of the thin-film process is disclosed in Japanese Patent Application Laid-Open No. 8-203737.
The second magnetic substrate 3 is bonded to the dielectric layer 2 through an adhesive layer 4.
An external electrode 5 is disposed to surround both ends of a structure including the first magnetic substrate 1, the dielectric layer 2 and the second magnetic substrate 3. The external electrode 5 is electrically connected through a lead line (not shown) to the first coil pattern 2a and the second coil pattern 2b. 
However, in the case of the conventional common-mode filter, in order to provide the dielectric layer 2 having the first coil pattern 2a and the second coil pattern 2b on the top surface of the first magnetic substrate 1, the top surface of the first magnetic substrate 1 should be accurately processed for a thin-film process.
Also, in order to perform a thin-film process on the top surface of the first magnetic substrate 1, it should be modified into a wafer shape or a shape capable of processes such as photo and deposition, leading to an inefficiency in the fabrication process.
Also, since the first magnetic substrate 1 for the conventional common-mode filter is a hard ferrite substrate, it may be broken and damaged during the fabrication process.